Mechanical pencil



Feb. 8, 1938. l. CHESLER MECHANICAL PENCIL Filed Dec. 5, 1955 ATTORNEYS Patented Feb. 8, 1938 PATENT QFFICE MECHANICAL PENCIL Isidor Chesler, New York, N. Y., assignor to Eagle Pencil Company, a corporation of Delaware Application December 5, 1935, Serial No. 52,969

3 Claims.

My present invention is concerned with mechanical pencils and more especially with the leads thereof.

As conducive to a. clear understanding of the invention, it is noted that in that type of mechanical lead pencil which is devoid of facilities for storing leads other than the single initially long lead in use, the annoyance arises that the lead may become. exhausted at a time and place when no refill lead is available.

It is an object of the present invention to afford conspicuous means to give the user sufiicient advance notice of the need for recharging the pencil, and this without the need for a transparent pencil casing or any modification whatsoever in the conventional construction of the casing or of the pencil mechanism.

According to the invention, the rear end of the lead is modified to give the desired notice, and this without adding materially to the cost of the lead, and without weakening the lead, or rendering it appreciably bulkier or impairing its utility for writing purposes.

In the accompanying drawing, in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. l is a View on a greatly enlarged scale of one embodiment of lead,

Fig. 2 is a cross-sectional view taken on the line 2-2 of Fig. 1,

Fig. 3 is a perspective view similar to Fig. 1 of a modification, and

Fig. 4 is a, view partly in cross-section showing the lead of Fig. 1 applied in one construction of mechanical pencil.

Referring now to Figs. 1 and 2 of the drawing, there is illustratively shown on a greatly enlarged scale the polygonal lead structure L patented in my prior Patent No. 2,011,270 of August 13, 1935. This lead illustratively is generally octagonal in crosssection with four pairs of contiguous edges 10 and H, each pair separated from the next pair by a concave side I2.

According to the present invention, the lead at its rear end is coated at l3 to present an appearance sharply contrasting with that of the length of the lead. Preferably this coating extends for approximately or of an inch along the length of the lead from one extremity thereof.

As a refinement the lead may also be provided with a similarly contrasting circumferential band M of the same or of different color (illustratively A of an inch wide) spaced about of an inch from the coating 13.

The tell-tale contrast is conveniently and effectively provided by spraying upon the area or areas described, clear lacquer with aluminium powder in suspension therein, by which expedient a conspicuous metallic coating or sheen is imparted at the rear end l3 and also at the band 14 if the latter is used. The lacquer coating as shown in the cross-sectional view of Fig. 2, covers the vertices of the lead and tends to protect the latter as hereinafter set forth. 10

While the lead as heretofore noted is useful with any of various designs of mechanical lead pencils, it has a preferred utility with that type of lead pencil in which a single long lead is used in which no magazine is provided for spare leads. 5 Such pencil is illustratively shown in Fig. 4, which shows a pencil of the general type of my prior Patent No. 1,956,271 of April 24, 1934. In that pencil, the clutch sleeve [5 has a wing or offset l6 riding in the helical track ll molded within the pencil casing i8 and is operated by means (not shown) preferably from the eraser ferrule IQ of the pencil.

The lacquer coating on the rear end of the pencil lead reinforces the sharp edges l9 and II 25 to minimize the chance for fracture or crumbling thereof when the lead is pushed into the clutch in charging the: pencil, and said lacquer also aids in the security of the clutch hold on the lead. Throughout the major period of use of the pencil, lead of the usual color is exposed at the pencil tip. As, however, the lead is advanced, the band I4 finally emerges through the pencil tip and its metallic sheen and the trace of such sheen appearing in the writing line warns the user of the need for recharging. The band thus gives an advance notice and when the corresponding length of lead has been consumed the pencil again writes in its regular color for a short period of time, until the covering 13 on the rear end is exposed and shows a silvery trace in the writing line. The writer in this embodiment will thus receive a second Warning of the need for recharging.

For most practical purposes it is sufficient, however, to dispense with the band l4 and to use merely the lacquered rear end 13 Such embodiment is shown in Fig. 3 in which there is illustratively shown an ordinary round lead 20 instead of the polygonal lead, the rear end of which is coated at 2| preferably by clear lacquer with aluminum powder as in Figs. 1 and 2.

For purposes of the present invention the lead may be and preferably is of the usual extruded structure uniform in cross section from end to end. The coating at the rear end of the lead, being of lacquer with the usual volatile carrier, affords in the finished construction, a coating so very thin as not appreciably to increase the diameter and to permit gripping of the lead at its coated end in the same conventional mechanical pencil clutch designed for the same lead without such coating. The lacquer after being sprayed upon, the lead end will promptly dry or set, leaving the aluminum powder particles bonded to the lead in a friable thin conspicuous coating which will powder off when scraped with a knife and which wears down with the lead in use and by virtue of its extreme thinness permits writing with Said coated end in substantially the color of the uncoated length of lead.

It will thus be seen that there is herein described an article in which the several features of this invention are embodied, and which article in its action attains the various objects of the invention and is well suited to meet the requirements of practical use.

As many changes could be made in the above construction, and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description 01' shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:-

1. Awriting lead for use in a mechanical pencil, said lead having a uniform cross section from end to end and having its rear end covered with a friable coating of conspicuous color contrasting with that of the lead, made up largely of minute solid particles adhering to the lead end, said coating being of sufficient thinness to permit effective writing with substantially the entire length of the lead in substantially the color of the uncoated lead, whereby a user is apprised of the need of recharging once said coated rear end is exposed in the mechanical pencil and may continue to write with said coated end until a new lead is available.

2. The lead as claimed in claim 1 in which the friable coating is of clear lacquer having powdered aluminum suspended therein.

3. A writing lead for use in a mechanical pencil, said lead having uniform polygonal crosssection from end to end presenting sharp longitudinal edges and having its rear end covered with a thin colored lacquer coating serving the combined function of an indicator to apprise of the need for recharging the pencil and as a reinforce to minimize the chance for fracture or crumbling of the lead at the end pushed into the lead clutch of a mechanical pencil.

ISIDOR CHESLER. 

